How many E. coli = 1 O.D. unit?
Zophonias O. Jonsson
zjons at vetbio.unizh.ch
Thu Jun 29 03:58:35 EST 1995
In article <3sb250$nbu at riscsm.scripps.edu>, "Edward K.L. Chan"
<echan at scripps.edu> says:
>
>Hi netters,
> I wonder if someone may be able to provide a reliable formula to calculate
>the number of DH5-alpha or XL1-Blue based on O.D. measurement. Thanks in
>advance.
I have seen various conflicting values for estimating E. coli titers from
OD600. They differ by more than an order of magnitute. Of course there
must be some strain variance but I doubt that it can be that much. The
values that I trust best are from a titration done by Sigridur H.
Thorbjarnardottir at the University of Iceland (since I know she is a
master in handling E. coli).
Doing a linear regression to her points I get the following equation:
Number of TG1/ml = 9.3 E8 x OD600
This should give a reasonable estimate, at least from OD600 = 0.1 to 0.8,
I don't guarantee higher values, you'll have to find that out for
yourself.
Hope this helps
Zophonias
_____________________________________________________________________
Zophonias O. Jonsson
Institut fur Veterinarbiochemie Tel: (41-1)-257-54-75
Universitat Zurich-Irchel Fax: (41-1)-362-05-01
Winterthurerstrasse 190
CH-8057 Zurich
Switzerland
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